provides guidance on considerations for involving users with disabilities,

includes notes on optimizing usability testing for accessibility issues, and

links to additional information on involving users throughout the design process.

While this resource is focused on Web accessibility evaluation, much of the guidance in it applies to a broad range of situations, including:

Design projects - Collaborating with people with disabilities early in a project helps designers and developers be more efficient and effective in addressing accessibility. For example, informal evaluations throughout development are more beneficial than only doing formal usability testing at the end of a project. In most cases, this involves:

finding a few people with disabilities,

including them throughout the development process to complete tasks on prototypes, and

discussing accessibility issues with them.

Usability and accessibility studies ranging from informal evaluation of a specific accessibility issue to large-scale general usability studies, and from gathering initial user requirements to evaluating existing designs.

People with disabilities are as diverse as any people. They have diverse
experiences, expectations, and preferences. They use diverse interaction
techniques, adaptive strategies, and assistive technology configurations. People
have different disabilities: visual, auditory, physical, speech, cognitive,
and neurological — and some have multiple disabilities. Even within
one category, there is extreme variation; for example, "visual
disability" includes people who have been totally blind since birth, people
who have distortion in their central vision from age-related degeneration,
and people who temporarily have blurry vision from an injury or disease.